src/mesa/vbo/vbo_split.c

   1
   2 /*
   3  * Mesa 3-D graphics library
   4  * Version:  6.5
   5  *
   6  * Copyright (C) 1999-2006  Brian Paul   All Rights Reserved.
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included
  16  * in all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  21  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  22  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  23  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  24  *
  25  * Authors:
  26  *    Keith Whitwell <keith@tungstengraphics.com>
  27  */
  28
  29 /* Deal with hardware and/or swtnl maximums:
  30  * - maximum number of vertices in buffer
  31  * - maximum number of elements (maybe zero)
  32  *
  33  * The maximums may vary with opengl state (eg if a larger hardware
  34  * vertex is required in this state, the maximum number of vertices
  35  * may be smaller than in another state).
  36  *
  37  * We want buffer splitting to be a convenience function for the code
  38  * actually drawing the primitives rather than a system-wide maximum,
  39  * otherwise it is hard to avoid pessimism.
  40  *
  41  * For instance, if a driver has no hardware limits on vertex buffer
  42  * dimensions, it would not ordinarily want to split vbos.  But if
  43  * there is an unexpected fallback, eg memory manager fails to upload
  44  * textures, it will want to pass the drawing commands onto swtnl,
  45  * which does have limitations.  A convenience function allows swtnl
  46  * to split the drawing and vbos internally without imposing its
  47  * limitations on drivers which want to use it as a fallback path.
  48  */
  49
  50 #include "main/glheader.h"
  51 #include "main/imports.h"
  52 #include "main/mtypes.h"
  53
  54 #include "vbo_split.h"
  55 #include "vbo.h"
  56
  57 /* True if a primitive can be split without copying of vertices, false
  58  * otherwise.
  59  */
  60 GLboolean split_prim_inplace(GLenum mode, GLuint *first, GLuint *incr)
  61 {
  62    switch (mode) {
  63    case GL_POINTS:
  64       *first = 1;
  65       *incr = 1;
  66       return GL_TRUE;
  67    case GL_LINES:
  68       *first = 2;
  69       *incr = 2;
  70       return GL_TRUE;
  71    case GL_LINE_STRIP:
  72       *first = 2;
  73       *incr = 1;
  74       return GL_TRUE;
  75    case GL_TRIANGLES:
  76       *first = 3;
  77       *incr = 3;
  78       return GL_TRUE;
  79    case GL_TRIANGLE_STRIP:
  80       *first = 3;
  81       *incr = 1;
  82       return GL_TRUE;
  83    case GL_QUADS:
  84       *first = 4;
  85       *incr = 4;
  86       return GL_TRUE;
  87    case GL_QUAD_STRIP:
  88       *first = 4;
  89       *incr = 2;
  90       return GL_TRUE;
  91    default:
  92       *first = 0;
  93       *incr = 1;                /* so that count % incr works */
  94       return GL_FALSE;
  95    }
  96 }
  97
  98
  99
 100 void vbo_split_prims( GLcontext *ctx,
 101                       const struct gl_client_array *arrays[],
 102                       const struct _mesa_prim *prim,
 103                       GLuint nr_prims,
 104                       const struct _mesa_index_buffer *ib,
 105                       GLuint min_index,
 106                       GLuint max_index,
 107                       vbo_draw_func draw,
 108                       const struct split_limits *limits )
 109 {
 110
 111    if (ib) {
 112       if (limits->max_indices == 0) {
 113          /* Could traverse the indices, re-emitting vertices in turn.
 114           * But it's hard to see why this case would be needed - for
 115           * software tnl, it is better to convert to non-indexed
 116           * rendering after transformation is complete, as is done in
 117           * the t_dd_rendertmp.h templates.  Are there any devices
 118           * with hardware tnl that cannot do indexed rendering?
 119           *
 120           * For now, this path is disabled.
 121           */
 122          assert(0);
 123       }
 124       else if (max_index - min_index >= limits->max_verts) {
 125          /* The vertex buffers are too large for hardware (or the
 126           * swtnl module).  Traverse the indices, re-emitting vertices
 127           * in turn.  Use a vertex cache to preserve some of the
 128           * sharing from the original index list.
 129           */
 130          vbo_split_copy(ctx, arrays, prim, nr_prims, ib,
 131                         draw, limits );
 132       }
 133       else if (ib->count > limits->max_indices) {
 134          /* The index buffer is too large for hardware.  Try to split
 135           * on whole-primitive boundaries, otherwise try to split the
 136           * individual primitives.
 137           */
 138          vbo_split_inplace(ctx, arrays, prim, nr_prims, ib,
 139                            min_index, max_index, draw, limits );
 140       }
 141       else {
 142          /* Why were we called? */
 143          assert(0);
 144       }
 145    }
 146    else {
 147       if (max_index - min_index >= limits->max_verts) {
 148          /* The vertex buffer is too large for hardware (or the swtnl
 149           * module).  Try to split on whole-primitive boundaries,
 150           * otherwise try to split the individual primitives.
 151           */
 152          vbo_split_inplace(ctx, arrays, prim, nr_prims, ib,
 153                            min_index, max_index, draw, limits );
 154       }
 155       else {
 156          /* Why were we called? */
 157          assert(0);
 158       }
 159    }
 160 }
 161